Upgrading pipe sizes

[fezster]

Isn't the point of this forum to share advice and knowledge so that you're better informed when you do get somebody in? Whilst I appreciate the point you are making, it's not through lack of trying on my part. I've had multiple people in, and it's possible I've been unlucky. However, the reality is probably that every person has a different solution depending on their own experience. Just as on here, some have said accumulator, some have said blockage, some have said pipe size. They're all guesses based on experience, which I appreciate, as they have given me ideas to look into. There'll be some here who understand the science behind it, and it's those I'm asking to help to explain what I'm seeing.

One of the questions I asked at the beginning of this thread is quite a straightforward one. Would 28mm pipes be beneficial even though the megaflo inlets and outlets are 22mm. Hopefully amongst all the noise about secondary returns and how incompetent the plumbers I've had so far are, somebody might be kind enough to answer the questions I raised.

 

[macackau]

Where abouts do you live? Someone on here might be able to help

 

[fezster]

I'm in se london. If there is someone, that'd be great.

I had two more guys round. Both said they'd probably upgrade the pipe size, but they couldn't guarantee it would fix it. One was very honest and said he'd recommend getting a commercial plumber as the distances are quite large. How would I go about finding commercial / semi commercial installers?

I also spoke to haetre sadia. They said this cylinder is capable of 74 l/m. They did say that it's possible the pressure reducing valve is malfunctioning and restricting flow. The problem I have with testing that is the outlets I have immediately after the prv is 15mm. It gives me 28 l/m. I don't think it's capable of delivering 50 l/m. Other than changing the prv speculatively, is there any other way of checking the flow through it?

 

[Pro Action]

I'd advise you find an unvented registered plumber to check the Megaflo installation before upgrading the pipe sizes. By law for safety purposes you must be unvented registered to work on a Megaflo.
The unvented registered plumber should also be able to help with the pipe sizing if that is necessary.

 

[fezster]

I'd advise you find an unvented registered plumber to check the Megaflo installation before upgrading the pipe sizes. By law for safety purposes you must be unvented registered to work on a Megaflo.
The unvented registered plumber should also be able to help with the pipe sizing if that is necessary.

Every plumber so far has been G3 certified. The cylinder was also serviced two weeks ago and the strainer cleaned. Thanks for the advice though.

 

[Staffy85]

I may be wrong but it sounds to me like your overall local water main pressure isn't good enough to support multiple outlets running at the same time, from post #7

" I also measured the pressure from a washing machine outlet (after my 3 bar megaflo prv) and got just over 1 bar pressure, with both taps running. Static pressure before the prv is 4 bar."

drops to just 1bar! I highly doubt upping the size to 28mm will help at all but that's my opinion and not fact...

 

[fezster]

I may be wrong but it sounds to me like your overall local water main pressure isn't good enough to support multiple outlets running at the same time, from post #7

" I also measured the pressure from a washing machine outlet (after my 3 bar megaflo prv) and got just over 1 bar pressure, with both taps running. Static pressure before the prv is 4 bar."

drops to just 1bar! I highly doubt upping the size to 28mm will help at all but that's my opinion and not fact...

Drops to 1 bar with 50 l/m flowing. I don't pretend to fully understand working pressure, but I think those are pretty good figures for multiple outlets.

However, I think the long and short of it is that even one outlet after my prv cannot deliver more than 28 l/m. I tried the washing machine pipe on its own, gave 28 l/m. Then put outside tap on (after prv) got 14 l/m on both (total 28) put the utility tap on and got 10, 10 and 8. These are all outlets after the prv and all within a few metres of it. The upstairs pipework doesn't even come into the equation. I'm more and more suspecting the prv is restricting flow.

Before my prv, one tap delivers 33 l/m and two taps deliver 50. The prv or the pipework just before and after it looks the suspect!

 

[Scott_D]

Post some pictures
Everyone is guessing based on your info and figures

 

[fezster]

Yes, of course. Here's pics going from right to left:

32mm MDPE incoming main.
Reduced to 25mm MDPE.
Reduced to 22mm copper.

Then it tee's down to the kitchen tap and outside tap.
Then the speedfit tee goes to an outside tap.
Then the water softener input and output, with bypass.

Then you have the blue isolation valve before the megaflo pressure reducing valve.
Immediately after this you have a tee going up to the balanced cold.
Then the megaflow pressure relief valve.
Speedfit reducing tee to outside tap.
There's a gate valve to isolate the megaflo input (not visible in the picture)
And you can just see the washing machine style tap before the megaflo inlet.

Hope that's useful.

 

[Pro Action]

If you are getting 1 bar working pressure on the ground floor the pressure on the upper floors is going to be less than this, so yes the working pressure could be a factor.

It's also possible that it could be a combination of factors such as pipe sizing and working pressure.